1. Field of the Invention
The present invention relates generally to a method and system for supplying a plurality of powderized materials in a mixed form. More specifically, the invention relates to a system for post-mixing a plurality of separate powderized materials transported via a carrier fluid in which mixing ratio and flow rate can be controlled. The invention also relates to a post-mix flux injection in a smelting process.
2. Description of the Background Art
As is well known, various powderized materials have to be introduced in smelting processes. For instance, coal injection has to be performed for a blast furnace, a flux injection must be performed into a LD converter and a plurality of fluxes are injected during hot metal pre-treatment. In the known processes of hot metal pre-treatment, fluxes for desiliconization, dephosphorization and desulfurization are used. Such hot metal pre-treatment processes are usually performed in torpedo cars or so forth. Conventionally, the hot metal pre-treatment process is separated into a desiliconization stage, a dephosphorization stage and a desulfurization stage. In the process stages, desiliconization agent, dephosphorization agent and desulfurization agent are injected. Since the desiliconization agent, deposphorization agent and desulfurization agent have respectively different compositions, it has been difficult to establish different composition of the agents from materials supplied from a common source. In this connection, the mutually different composition of agents are prepared into a post-mix and stored in reservoirs at different positions. During such hot metal pre-treatment processing, the torpedo cars have to travel along a processing line for performing different stages of pre-treatment. Flux injection at desiliconization stage, dephosphorization stage and desulfurization stage all have been disclosed in the Japanese Utility Model Second (examined) Publication (Jikko) No. Showa 57-21032, published on, and the Japanese Patent First (unexamined) Publication (Tokkai) No. Showa 57-67422, for example. Each of these publications discloses a flux injection system comprising a single flux reservoir tank and a single lance. The flux in the powder stage is carried with a gaseous state carrier fluid at a controlled rate.
Such conventional hot metal pre-treatment processes are inconvenient, since they require travelling of the torpedo cars from one stage to the next stage. Furthermore, at every stage, a slag-off operation is required. Such necessities make the hot metal pre-treatment process inefficient.